Install pre-hung door in older home

Hi All,
I want to install some new interior doors in my home. I was making some measurements when I noticed that the wall studs were 3 5/8", not 3 1/2".
Have any of you come across this? The jambs on current pre-hung doors are 4 1/2". With the wall studs being 3 5/8", the drywall surface would be higher than the face of the jamb. Should I put some kind of stock on the face of the jambs to bring them out?